Cytogenetic and loss-of-heterozygosity (LOH) studies have demonstrated that deletions of the chromosome 3 short arm (3p) occur at very high frequency in all forms of lung cancer (universal loss in SCLC AND about-80% in NSCLC). These observation suggest that 3p encodes one or more tumor suppressor genes whose loss is critical to lung cancer development and progression. Data from our laboratory and others have demonstrated 4 separate, recurring homozygous deletion regions on 3p. Project 1 will investigate the role of 3p loss in lung cancer and pre-malignant lesions. A primary goal of t his project is the translation of our experimental results into clinically useful approaches. While the most sensitive diagnostic 3p reagents will come from the actual target genes, a major advance in both LOH and FISH detection will result, respectively, from the use of highly polymorphic PCR-based markers and hybridization probes closely representing the target gene regions. To accomplish this, we will precisely define the affected 3p intervals and develop additional corresponding polymorphic markers and FSH probes that will be applied to the analysis of tumors, dysplastic biopsies and sputa. Not only will these reagents provide a powerful means for detecting small 3p alterations in diagnostic sample but they will facilitate the molecular cloning of target genes through improved definition of critical regions. B working with a common set of samples, we will be able to correlate our 3p results with those of other SPORE members and inter-SPORE collaborators investigating chr 9, p53, RB, p16INK4, cyclin D1 and other chromosomal loci frequently affected in lung cancer. From these combined data, we hope to gain a comprehensive understanding of genetic changes which characterize each type of lung cancer or pre-neoplastic lesion, and to begin to address issues of prognosis and predictability. We will further characterize and conduct gene searches within two selected target regions (distal 3p21.3 and 3p12(13) that undergo recurrent homozygous deletion as well as well as perform functional assays of candidate tumor suppressor genes. This latter effort will include transfection experiments of candidate genes into lung cancer cell lines to determine their effect on growth and tumorigenesis. Lastly, we will identify the region of chromosome 3 which encodes a recently recognized inhibitor of telomerase activity.